1. Field of the Invention
This invention relates to a video muting apparatus which is used in a television receiver having a displaying means consisting of a picture tube and controls the time of starting a video signal feeding operation of feeding a video signal to this picture tube.
2. Description of the Related Art
Generally, in a television receiver having a displaying means consisting of a picture tube, the time of starting a video signal feeding operation of feeding a video signal to the picture tube is controlled. In a controlling system for controlling the time of starting this video signal feeding operation, the operation of feeding the video signal to the picture tube will be stopped during the period from the time of inputting the power source of the television receiver until the channel selection is completed and will be started immediately after the stopping period ends.
When the period from the power source input until the channel selection is completed is short, the cathode electrode of the image receiving tube will not be heated by a heater up to a predetermined temperature and the video signal feeding operation will be started while the cathode electrode is not heated up to the predetermined temperature. When the video signal feeding operation is started while the temperature of the cathode electrode is low, the cathode electrode will be subjected to a large load and will be likely to deteriorate. As a result, a color slip or the like or the video will be caused by the deterioration of the cathode electrode and the quality of the video displayed in the picture tube will remarkably reduce.
In order to prevent the deterioration of the cathode electrode, it is considered to add a capacitor of a large capacity or the; like to the circuit and to elongate the period from the power source input until the video signal feeding to the picture tube is started. Then, the capacitor will become so large that the cost will increase and the circuit scale will become large. The rising time until the video is displayed in the picture tube will be always long and the rising performance will reduce.
As described above, in the controlling system for controlling the time of starting the operation of the video signal feeding to the picture tube in the conventional television receiver, the cathode electrode will be likely to deteriorate and the quality of the video will be likely to be remarkably reduced by the deterioration of the cathode electrode.